Protective factor - SPF (Sun Protection Factor) of a sunbathing preparation should provide protection of your skin from the harmful UVB and UVA beams of the sun radiation. The number of SPF expresses, how many times you can prolong your time spent in the sun without burning your skin. The UV filters are of two types - chemical substances, which absorb the UV radiation selectively, and substances which reflect or disperse sun beams. The sunbathing preparations should have SPF 10 at minimum. Lips, ears, cheekbones, and fetlocks should be protected with a higher SPF.